Many earthmoving operations require a finished grade or cut that meets strict specifications. One common way of monitoring and controlling this type of earthmoving job is to use a laser generated plane to define the desired finished grade, and to use laser detectors mounted on the earthmoving machine to guide the earthmoving implement in the desired manner in response to the elevation of the laser plane.
In addition to controlling the elevation of the implement relative to the laser plane, other sensors are often used to monitor and control the angle of inclination of the implement relative to the machine. Such sensors are common in the art and include a variety of types of sensors, such as bubble sensors, pendant angle sensors, resolvers, and the like.
As an example of a combination of the above two technologies, in U.S. Pat. No. 4,273,196, Etsusaki et al disclose a system using both laser receivers and inclinometers. The laser receivers control the elevation of an earthmoving blade and the inclinometer measures the tilt of the blade and compares the measured tilt with the desired tilt as selected by the operator.
The use of tilt sensors in addition to the use of laser receivers requires separate sets of components for the laser detection and for the tilt detection. This adds to the cost and complexity of the implement position sensing system. A preferred configuration would be to combine the functions of the two sets of sensors into one set of components.
In U.S. Pat. No. 4,807,131, Clegg discloses a system using two sets of laser detectors mounted at both ends of an earthmoving blade. The system can measure the side to side slope of the blade by comparing the difference in elevation of the two laser receivers, as well as measure the elevation of the blade using the laser system. However, the laser system cannot determine the fore to aft pitch of the blade, so additional pitch sensors are still required.
The present invention is directed to overcoming one or more of the problems as set forth above.